A new study published in the American Journal of Clinical Nutrition examined the association between dietary glycemic index and the 10 year incidence of AMD in the Blue Mountain Eye Study population.
This was a population-based study with 3,654 participants over 49 years of age. Volunteers were examined at the beginning (1992-1994); then were reexamined after 5 years and again after 10 years.
Over 10 years, 208 of the participants developed early AMD. After adjusting for age, smoking, other risk factors, and dietary constituents, a higher average dietary glycemic index was associated with an increased 10 year risk of early AMD. Conversely, a greater consumption of cereal fiber and breads and cereals (predominantly lower glycemic index foods such as oatmeal) was associated with a reduced risk of early AMD. No relation was observed with advanced AMD. The research suggests that a high-glycemic-index diet is a risk factor for early AMD, and low-glycemic-index foods such as oatmeal may protect against early AMD.
American Journal of Clinical Nutrition, Vol. 88, No. 4, 1104-1110, October 2008
Friday, November 7, 2008
Decreased antioxidant levels increase risk of age-related macular degeneration with exposure to sunlight
In a recent study (titled the European Eye Study), over 4,400 participants over age 65 were analyzed for the presence of macular degeneration. Their blood plasma was evaluated for vitamins C and E, the carotenoids lutein and zeaxanthin, and the mineral zinc. Each individual also completed a questionnaire regarding their typical exposure to sunlight. This was used to estimate blue light exposure from visible light, which is known to contribute to the development of macular degeneration.
Early stage macular degeneration was detected in 2,182 participants, and 101 had the advanced form of the disease. The research found no association between blue light exposure and early macular degeneration. However, among participants in the lowest quartile (25 percent) of serum vitamin C, zeaxanthin, vitamin E and zinc, exposure to blue light significantly increased the risk of advanced macular degeneration.
Arch Ophthalmol 2008 Oct;126(10):1396-403
Early stage macular degeneration was detected in 2,182 participants, and 101 had the advanced form of the disease. The research found no association between blue light exposure and early macular degeneration. However, among participants in the lowest quartile (25 percent) of serum vitamin C, zeaxanthin, vitamin E and zinc, exposure to blue light significantly increased the risk of advanced macular degeneration.
Arch Ophthalmol 2008 Oct;126(10):1396-403
Lutein and zeaxanthin may improve visual performance and reduce the effects of glare
Healthy subjects with an average age of 23.9 were assigned to receive daily supplements of lutein (10 mg) and zeaxanthin (2 mg) for six months. The subjects' eyes were then tested for the effects of glare as experienced in everyday situations, including being outdoors on bright days, lengthy sessions of looking at a computer monitor, and nighttime exposure to oncoming headlights.
Following six months of supplementation, the participant's average macular pigment optical density (MPOD) increased significantly from the average value at the beginning of the study. MPOD is a measure of the eye's ability to filter short-wave light.
After testing the subjects for their performance in visual tasks following glare, researchers concluded that four to six months of supplementation with lutein and zeaxanthin significantly reduced the detrimental effects of the exposure and improved visual performance.
Optom Vis Sci 2008 Feb;85(2):82-8
Following six months of supplementation, the participant's average macular pigment optical density (MPOD) increased significantly from the average value at the beginning of the study. MPOD is a measure of the eye's ability to filter short-wave light.
After testing the subjects for their performance in visual tasks following glare, researchers concluded that four to six months of supplementation with lutein and zeaxanthin significantly reduced the detrimental effects of the exposure and improved visual performance.
Optom Vis Sci 2008 Feb;85(2):82-8
American Academy of Pediatrics increases vitamin D recommendations
The American Academy of Pediatrics issued a press release regarding a new clinical report titled "Prevention of Rickets and Vitamin D Deficiency in Infants, Children, and Adolescents." In this new report, the AAP has updated the amount of vitamin D they formally recommend for children from 200 IU per day to 400 IU per day.
"We are doubling the recommended amount of vitamin D children need each day because evidence has shown this could have life-long health benefits," said Frank Greer, MD, FAAP, chair of the AAP Committee on Nutrition and co-author of the report. "Supplementation is important because most children will not get enough vitamin D through diet alone."
This updated recommendation is largely based on data from clinical trials performed since 2003 (when the original recommendation of 200 IU per day was given). This new data has demonstrated not only a wide safety margin for vitamin D supplementation, but also a surprising occurrence of vitamin D deficiency, particularly in exclusively breastfed infants who are not supplemented with vitamin D.
"Breastfeeding is the best source of nutrition for infants. However, because of vitamin D deficiencies in the maternal diet, which affect the vitamin D in a mother's milk, it is important that breastfed infants receive supplements of vitamin D," said Carol Wagner, MD, FAAP, member of the AAP Section on Breastfeeding Executive Committee and co-author of the report. "Until it is determined what the vitamin D requirements of the lactating mother-infant dyad are, we must ensure that the breastfeeding infant receives an adequate supply of vitamin D through a supplement of 400 IU per day."
Quotations taken from the formal AAP press release available at http://www.aap.org/pressroom/nce/nce08vitamind.htm To review the new clinical report in its entirety, please visit http://www.aap.org/new/VitaminDreport.pdf
"We are doubling the recommended amount of vitamin D children need each day because evidence has shown this could have life-long health benefits," said Frank Greer, MD, FAAP, chair of the AAP Committee on Nutrition and co-author of the report. "Supplementation is important because most children will not get enough vitamin D through diet alone."
This updated recommendation is largely based on data from clinical trials performed since 2003 (when the original recommendation of 200 IU per day was given). This new data has demonstrated not only a wide safety margin for vitamin D supplementation, but also a surprising occurrence of vitamin D deficiency, particularly in exclusively breastfed infants who are not supplemented with vitamin D.
"Breastfeeding is the best source of nutrition for infants. However, because of vitamin D deficiencies in the maternal diet, which affect the vitamin D in a mother's milk, it is important that breastfed infants receive supplements of vitamin D," said Carol Wagner, MD, FAAP, member of the AAP Section on Breastfeeding Executive Committee and co-author of the report. "Until it is determined what the vitamin D requirements of the lactating mother-infant dyad are, we must ensure that the breastfeeding infant receives an adequate supply of vitamin D through a supplement of 400 IU per day."
Quotations taken from the formal AAP press release available at http://www.aap.org/pressroom/nce/nce08vitamind.htm To review the new clinical report in its entirety, please visit http://www.aap.org/new/VitaminDreport.pdf
Oily fish intake and dietary omega-3s may improve eye health
Fish intake, the major source of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), may reduce the risk of age-related macular degeneration (AMD). There are two types of AMD: wet and dry. Of these two types, wet AMD is the primary cause of vision loss.
In a study recently published in the American Journal of Clinical Nutrition, researchers recruited 105 people (age 65 and over) with wet AMD and 2170 healthy people to act as controls, then compared their dietary habits using questionnaires. The scientists then investigated the association of oily fish and dietary DHA and EPA with wet AMD.
Compared to people who consumed less than one portion of fish per week, participants who consumed at least one serving of oily fish per week had a 50 percent reduction in risk of developing wet AMD. In addition, people who got at least 300 mg per day of DHA and EPA were 68 and 71 percent less likely to have wet AMD than those with lower consumptions.
The results of this study support previous research indicating a protective benefit of omega-3s against the onset of AMD. The benefit may be due in part to their important role in the layer of nerve cells in the retina.
American Journal of Clinical Nutrition, Vol. 88, No. 2, 398-406, August 2008
In a study recently published in the American Journal of Clinical Nutrition, researchers recruited 105 people (age 65 and over) with wet AMD and 2170 healthy people to act as controls, then compared their dietary habits using questionnaires. The scientists then investigated the association of oily fish and dietary DHA and EPA with wet AMD.
Compared to people who consumed less than one portion of fish per week, participants who consumed at least one serving of oily fish per week had a 50 percent reduction in risk of developing wet AMD. In addition, people who got at least 300 mg per day of DHA and EPA were 68 and 71 percent less likely to have wet AMD than those with lower consumptions.
The results of this study support previous research indicating a protective benefit of omega-3s against the onset of AMD. The benefit may be due in part to their important role in the layer of nerve cells in the retina.
American Journal of Clinical Nutrition, Vol. 88, No. 2, 398-406, August 2008
Low vitamin D levels lead to poor physical performance in the elderly
In addition to its role in bone health, vitamin D is thought to play a role in musculoskeletal function. In a recent study, researchers examined the association between vitamin D status and physical performance in a sample of 976 persons over the age of 65. The physical performance of the subjects was analyzed using a short physical performance battery (SPPB) and handgrip strength. The SPPB tests included walking speed, ability to stand from a seated position, and ability to maintain balance in progressively more challenging positions. Over 28% of the women and 13% of the men had vitamin D levels low enough to be considered a deficiency. Nearly three-fourths of the women and over half of the men had vitamin D levels that were considered insufficient. Among subjects with low vitamin D levels, physical performance and grip strength were significantly lower than that of participants who did not have reduced levels. The finding remained valid after taking into consideration other factors (such as season of the year and physical activity levels). Given the high prevalence of vitamin D deficiency in older populations, additional studies examining the association between vitamin D status and physical function are needed. Current vitamin D recommendations are based on its role in bone health, although emerging research indicates vitamin D may also play important roles in preservation of muscle strength and physical function, as well as potential preventative roles in conditions such as cancer.
The Journals of Gerontology Series A: Biological Sciences and Medical Sciences 62:440-446 (2007)
The Journals of Gerontology Series A: Biological Sciences and Medical Sciences 62:440-446 (2007)
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